Save It As Codemirror Theme Builder/index.html :

Our HTML markup is working properly I have checked if you face any difficulty let me know in the comment section below.
Without CSS our this script (Codemirror Theme Builder) will never look lovely. So here we are, our HTML markup is ready now we have to personalize our HTML and it can be done using CSS.

So below is the CSS code for our HTML markup and you have to save it with the filename as provided. Make a new folder called css and put this file to that folder.

The CSS code provided below can have some errors because the source code is automatically encoded so I recommend you to download the project files from the download link provided below.

Save It As Codemirror Theme Builder/css/style.css :

To make customizations we have used CSS all cascading style sheets code.
So we have written HTML markup and customised it and now we will add some functionality in this project (Codemirror Theme Builder).

To make this project (Codemirror Theme Builder) work properly for that we will use JavaScript.

So here is a JavaScript for our project (Codemirror Theme Builder) and also save it with the filename as provided. Make a new folder called js and put this file to that folder.

The JavaScript code provided below can have some errors because the source code is automatically encoded so I recommend you to download the project files from the download link provided below.

Save It As Codemirror Theme Builder/js/e2eac470cd7c51a1f14efaf2c.js :

Code is very much lenthy please download the project file.

JavaScript is the necessary code of this tool which makes this tool work properly. If JavaScript code is excluded from this tool then this tool will not work.

Ending :

So here we are, We have done and our project Codemirror Theme Builder is ready now you can save all the files as provided.
Like CSS files in css folder and JavaScript files in a JS folder name. Below is folder tree of the files and folders of this project.